Stereovision is one of the most important factors when a 3D content is perceived. Stereovision is a phenomenon in which two images for a particular object are combined into one image to provide a three-dimensional perception when the two images are viewed in such a manner that a left eye takes a view of a left image and a right eye takes a view of a right image at a visual range (approximately 25 cm).
Recently, a 3D content is in high demand as 3D display devices such as a 3D TV, 3D movies, etc. come into wide use. However, statistics show that about 15% of the population do not perceive or enjoy a three-dimensional effect.
Regarding the stereovision, the protrusion degree (depth degree) for an object in a 3D image is a main factor to perceive a 3D image three-dimensionally. 3D contents makers assign a certain protrusion degree to various objects which are contained in the 3D image, respectively. However, people perceive the protrusion degree differently with regard to objects which are made to have the same protrusion degree and therefore, people cannot perceive the protrusion degree which the maker intended.
Regarding the protrusion degree, a viewer feels dizzy when he sees a 3D image having a high protrusion degree which exceeds a predetermined protrusion degree. A viewer who is sensitive to the protrusion degree may be apt to feel dizzy in case of a normal protrusion degree.
Recently, to overcome the problem, a study is being conducted to control the protrusion degree for the objects in a 3D image. If a viewer adjusts the protrusion degree of the 3D image to a protrusion degree suitable for the viewer, the viewer will be able to see the 3D image more clearly and more three-dimensionally.
Here, if 3D contents are developed for which the protrusion degree can be controlled, it is needed to measure the protrusion degree which each individual perceives. That is, at first, a protrusion degree which an individual perceives compared to a protrusion degree of normal people must be determined. Based on this, the protrusion degree of a 3D content which a viewer is watching will be adjusted.